The Guns of August is a very readable book about the origins of WW One. Part of the issue, a large part, were the security agreements between various nations that collided. Britain for example had guaranteed Belgium, and the German Schlieffen plan involved a wheel attack through Belgium into the French proper. Russia had guaranteed Serbia, Austria wanted to punish Serbia. Germany was on the side of Austria. France was on the side of Russia. Dominoes.
A weird thing is that the King of England, the Kaiser, and the Tsar, had the same grandmother, they were first cousins.
The Terms Kaiser and Tsar come from Caesar, which in latin is pronounced with a hard C, Kaiser.